Spark-plug and method of forming the same.



` A. SCHMIDT. SHARK PLUG' AND METHOD OF FORNHNG THE SAME. APPLICATIONFILED AUGJT, 1913.

1,174,61S- Patented Mar. 7,1915.

UNITED STATES ALBERT SCHMIDT, 0F FLINT, MICHIGAN, SSIGNOR TO CHALIGNGNTN CCNE' fil/HY,

OF FLINT, MIGHGAN, A CORPGRATSN GLF MCHGN.

SPARK-PLUG AND METHOD 0F FORMING THE SAME.

Application le August 21, 1913.

To all whom t may concern:

Be it known that l, ALBERT SCHMIDT, a citizen of the Republic of France,residing at Flint, in the county of Genesee and State of Michigan, haveinvented certain new and useful Improvements in Spark-Plugs and Methodsof Forming the Same, ot which the following is a. specification,reference being had therein to the accompanying drawings.

The invention relates to spark plugs, and has for its object thesimplilication of the method of manufacture and reduction in cost or"same.

ln the present state of the art, it is usual to form spark plugs with anouter metallic easing having a hexagonal portion for engagement of awrench and an integral threaded nipple of reduced diameter forengagement with the aperture in the engine casing. lt is also usual toprovide a shoulner within the metallic casing, against which theinsulator bears, and a threaded bushing between the insulator and thecase for hold ing the former to its seat upon said shoulder.

lilith my improvedv construction the threaded bushing may be entirelydispensed with by forming a threaded'engagement loetween the nippleportion and the hexagonal portion of the casing. Furthermore, theconstruetionlis one which may be manuvfactured vby a different method,viz. one in which the hexagonal and nipple portions are cut .fromseparate pieces oi' stock, wherehy waste is eliminated.

ln thepdrawings: Figure l is a central longitudinal section through theeasing ot the spark plug, showing the insulator secured thereto; andFig. 2 is a perspective view of the two-memhers of the casing detached,and illustrating the manner in which they are out from the stock.

With my improved method of manufao4 ture, I proceed as follows: A har ofhei:- ag'onal stockof suitable dimensions, indicated by dotted lines atA, Fig. 2, is bored, internally threaded and 'otherwise 'fashioned toform the member l5. This ine-ailier Specification of Letters Patent.

relation.

Patented Mar. i2

Serial No. 786,601.

H being placed between the should .l on this insulator and an opposed shder l termed by the inner end oi' the t* lf desired an inner bushing mayhe placed between i the member i3, after which ne n'iemhers B and l" arerelatively rotated to clamp the shoulder l upon the shoulder lVhen theparts are thus assembled, ay 'lo spark plug is formed which dispenses'with the usual threaded bushing, and which is in every way as strongand gas proof.

The nipple is secured into the engine easing hy engaging the hexagonalportion 'with the wrench or other tool, and to prevent relative movementof the members B and F". some loc such a set screw L is r these parte infixed The oost' ot the construction reduced, both hy reason ot themethod at manufacture and amount et stool-1 which is wastes.

lt will he noted that with the. tion or" plug as describen inserted themetallic ci side and bears against an upon said ca heretofore quires adodevice for securing in position.

What claim a." my invent-ion is:

ola. casing comprising' con nipple portion adapted easing, and aalseparat-e members navto engage an e'Y portion,

ing a. threaded engagement with each other, sadpolygonal portion formingthe head for said nipple portion, a locking means to prevent relativemovement of said members, and an insulator clamped between said Ymembers.

